High pressure torsion to refine grains in pure aluminum up to saturation : Mechanisms of structure evolution and their dependence on strain

High-pressure torsion was used for the deformation processing of high-purity aluminum (4N-Al), while high-resolution electron-backscatter diffraction was used for the analysis of evolution of qualitative and quantitative microstructural characteristics. This study reveals a rather full picture of microstructure evolution in the high stacking fault energy fcc material and makes a continuous link between deformation microstructures at low, high and very high strains. Three stages of the microstructure evolution in 4N-Al at ambient temperature have been found: (i) the first stage in the range ∈ eq ≤ 1; (ii) a transition stage in the range 1eq ≤ 8; and (iii) a saturation stage in the range ∈ eq 8. In stages (i) and... (More)

High-pressure torsion was used for the deformation processing of high-purity aluminum (4N-Al), while high-resolution electron-backscatter diffraction was used for the analysis of evolution of qualitative and quantitative microstructural characteristics. This study reveals a rather full picture of microstructure evolution in the high stacking fault energy fcc material and makes a continuous link between deformation microstructures at low, high and very high strains. Three stages of the microstructure evolution in 4N-Al at ambient temperature have been found: (i) the first stage in the range ∈ eq ≤ 1; (ii) a transition stage in the range 1eq ≤ 8; and (iii) a saturation stage in the range ∈ eq 8. In stages (i) and (ii), grain subdivision and typical features of deformation microstructures are found. Starting from stage (ii), formation of small equiaxed (sub)grains surrounded by high-angle boundaries (HABs) is found together with minor increase in the average subgrain size. At stage (iii), recrystallized-like microstructure mostly consisting of the dynamically stable equiaxed subgrains surrounded by HABs dominates the microstructure.

@article{906a68d6-10f5-41a4-902c-a8332885a1b9,
abstract = {<p>High-pressure torsion was used for the deformation processing of high-purity aluminum (4N-Al), while high-resolution electron-backscatter diffraction was used for the analysis of evolution of qualitative and quantitative microstructural characteristics. This study reveals a rather full picture of microstructure evolution in the high stacking fault energy fcc material and makes a continuous link between deformation microstructures at low, high and very high strains. Three stages of the microstructure evolution in 4N-Al at ambient temperature have been found: (i) the first stage in the range ∈ <sub>eq</sub> ≤ 1; (ii) a transition stage in the range 1eq ≤ 8; and (iii) a saturation stage in the range ∈ <sub>eq</sub> 8. In stages (i) and (ii), grain subdivision and typical features of deformation microstructures are found. Starting from stage (ii), formation of small equiaxed (sub)grains surrounded by high-angle boundaries (HABs) is found together with minor increase in the average subgrain size. At stage (iii), recrystallized-like microstructure mostly consisting of the dynamically stable equiaxed subgrains surrounded by HABs dominates the microstructure.</p>},
author = {Orlov, Dmitry and Kamikawa, Naoya and Tsuji, Nobuhiro},
issn = {1478-6435},
keyword = {aluminum,EBSD,grain refinement,high pressure torsion,microstructure},
language = {eng},
month = {06},
number = {18},
pages = {2329--2350},
publisher = {Taylor & Francis},
series = {Philosophical Magazine Letters},
title = {High pressure torsion to refine grains in pure aluminum up to saturation : Mechanisms of structure evolution and their dependence on strain},
url = {http://dx.doi.org/10.1080/14786435.2012.671548},
volume = {92},
year = {2012},
}